The present invention relates generally to radio equipment for wireless telecommunications and, more particularly, to a method for adding a leaf node to a multi-node base station.
In the implementation of base stations within wireless telecommunications networks there has been a trend for the distribution of the base station functionality across more than one physical device. This trend is particularly marked in the network architectures of the 3GPP Standards (such as recent releases of UMTS (Universal Mobile Telecommunications System) and LTE (Long Term Evolution)) and in WiMAX (Worldwide interoperability for Microwave Access).
To facilitate communication of data between the distributed base station subsystems, an interface specification, Common Public Radio Interface, CPRI, has been established [CPRI version 5.0 published 21 Sep. 2011]. Using CPRI, it is possible to arrange the base station subsystems in a chain. Each distributed base station needs at least one controller subsystem (to establish network interfaces between the base station and the core network of a telecommunications network as well as to other base stations) and at least one radio access subsystem (for providing an air interface between the base station and communications terminals, such as mobile phones and computing devices with suitable wireless modem equipment). At least one bidirectional interface, referred to as a “CPRI link”, connects the controller subsystem directly to the radio access subsystem. Further radio access subsystems can be attached to subsystems already linked using CPRI links, thereby creating a chain.
Maintaining CPRI links requires careful arrangement of the signaling between existing subsystems so that timing flows remain predictable. Adding a new subsystem node may disrupt this careful arrangement, leading to unexpected failures and, potentially, loss of part, or all, of the radio access network provided by distributed base station arrangements.